People ask multiple people for advice because you get different kinds of answers, like some advice can help you and some advice can not help you. Their are two kinds of advises people can give you.

Getting different types of answers from people are very helpful, lets say that you got into trouble and had to deal with consequences then the principal said " I'm going to give you advice, next time stay out of trouble and think about what you do before you show action". That is good advice so you will not do the same thing you did last time, most advice that help people will not help you and you might do it again.

Whether, you get advise from people think about it first because you know when it does no help you or it does not feel like the right advise for you, lets say you end up in trouble again but this time someone tells you to talk back or smack that person, that is advise you do not want to listen to because you will learn from it.

Multiple opinions can help someone make a better choice, like getting advice from lots of people will help you, like if you want to do the right thing and do what is best for you, you will have to get advise from multiple people because it is not as easy as you think it is.

Why do people ask more than one person is because other people have different advise and opinions from other people.